fission

1 of 2

noun

fis·​sion ˈfi-shᵊn How to pronounce fission (audio)
-zhᵊn
1
: a splitting or breaking up into parts
2
: reproduction by spontaneous division of the body into two or more parts each of which grows into a complete organism
3
: the splitting of an atomic nucleus resulting in the release of large amounts of energy
fissional adjective

fission

2 of 2

verb

fissioned; fissioning; fissions

intransitive verb

: to undergo fission

transitive verb

: to cause to undergo fission

Examples of fission in a Sentence

Recent Examples on the Web
Noun
The Soviet Union launched around 40 military satellites powered by fission nuclear reactors, and some of these are still in Earth orbit today. Stephen Clark, Ars Technica, 4 Apr. 2024 But basic information about the standard type of fission weapon, known as an implosion device, has long been known publicly. IEEE Spectrum, 17 June 2024
Verb
Most atoms do not fission, but the isotopes of certain elements, such as uranium-235, are fissile. Washington Post, 28 Apr. 2022 The point is that by analyzing the array of radioactive fission products – those that can be captured and analyzed – nuclear forensic specialists can start to figure out if the atoms that fissioned were U-235, Pu-239, or (in some cases) U-238. Andrew Karam, Popular Mechanics, 7 Jan. 2016 See all Example Sentences for fission 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'fission.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Noun

borrowed from Latin fissiōn-, fissiō, from fid-, variant stem of findere "to split, cleave" + -tiōn-, -tiō, suffix of verbal action — more at bite entry 1

Verb

derivative of fission entry 1

First Known Use

Noun

circa 1617, in the meaning defined at sense 1

Verb

1929, in the meaning defined at intransitive sense

Time Traveler
The first known use of fission was circa 1617

Dictionary Entries Near fission

Cite this Entry

“Fission.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fission. Accessed 16 Jul. 2024.

Kids Definition

fission

1 of 2 noun
fis·​sion ˈfish-ən How to pronounce fission (audio)
 also  ˈfizh-
1
: a splitting or breaking up into parts
2
: a method of reproduction in which a living cell or body divides into two or more parts each of which grows into a whole new individual
3
: the splitting of an atomic nucleus resulting in the release of large amounts of energy

fission

2 of 2 verb
fissioned; fissioning
ˈfish-(ə-)niŋ,
ˈfizh-
: to go through or cause to go through fission

Medical Definition

fission

noun
1
: a method of reproduction in which a living cell or body divides into two or more parts each of which grows into a whole new individual
2
b
: the splitting of an atomic nucleus resulting in the release of large amounts of energy

called also nuclear fission

fission verb
fissioned; fissioning ˈfish-(ə-)niŋ also ˈfizh- How to pronounce fission (audio)
fissional adjective

More from Merriam-Webster on fission

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!